US 2005/0054996 and US 2005/0137526 describe bowel management apparatus including a silicone tube having at its distal end a balloon cuff that may be inflated to locate the distal end of the tube inside a wearer's rectum. The proximal end of the tube is fitted with a connector for making a connection to a fecal collector chamber. It is difficult to find an ideal single material that exhibits all of the desired characteristics for making the tube. Silicone is used for its biocompatibility, flexibility and comfortable wear characteristics. However, silicone is known to have a relatively high gas transpiration (or transmission) rate, which might lead to malodors leaking through the material forming the tube, especially if the tube has a relatively long run to the fecal collection chamber. The human nose is especially sensitive to flatus, and foul odors are embarrassing and unpleasant for the wearer and caregivers.
In US 2005/0054996, a parylene coating is applied to the surfaces of the silicone material to improve its odor barrier properties. However, in some cases, the parylene coating might not be ideal because:                (i) the parylene coating tends can be highly crystalline, and so might be vulnerable to micro-cracking when the silicone tube is flexed or twisted or stretched in use, leading possibly to a reduction in the integrity of the odor barrier;        (ii) the parylene coating tends to be relatively thin. Any irregularities in the deposited thin coating could further risk the integrity of the odor barrier. For example, the odor barrier of parylene at 25 thickness is reported to be 30 cc/m2/day at 23° C. However, a thin coating in the range of 1-2 μm thickness could result in an oxygen transmission rate much higher, in the 380-760 cc/m2/day range, which might be too high to provide sufficient odor barrier. Any micro-cracking in parylene would even worsen already compromised thin layer of barrier coating;        (iii) the coating process involves polymerizing and vacuum depositing the parylene onto the silicone tube, which is a difficult and expensive manufacturing process, thus increasing the manufacturing costs; and        (iv) there is a requirement to mask some key parts of the device against coating by parylene, which further complicates the manufacturing process;        
For reference, other bowel and stoma appliances employing silicone based tubes include U.S. Pat. Nos. 4,381,765, 4,662,890, 4,721,508 and 5,569,216, and published U.S. Patent Applications 2004/0039348, 2006/0100595 and 2006/0189951. However, none of these publications address the issue of odor leakage through the silicone material.
The present invention has been directed to enhancing the characteristics of the silicone tube for handling malodoriferous matter. In particular, it would be desirable to provide an alternative odor barrier technique for the silicone tube, which can achieve at least approximately the same degree of odor barrier as a parylene coating, but which may be less disadvantageous.